1. Field of the Invention
The present invention relates to baths for cleaning semiconductor wafers, and more particularly, relates to an apparatus for evenly distributing a gas throughout such a bath.
2. Description of the Prior Art
In the electronics industry, particularly in the manufacture of semiconductor wafers, baths are commonly used for cleaning semiconductor wafers.
One such example is the cleaning of semiconductor wafers in a sulfuric acid (H.sub.2 SO.sub.4) bath. In such baths, ozone gas (O.sub.3) is ejected into the bath for purposes of oxygenating the acid and extending the useful life of the acid. The byproduct of injection of the ozone into the acid is oxygen. Ozone is used in place of H.sub.2 O.sub.2 (hydrogen peroxide). The by product of H.sub.2 O.sub.2 in sulfuric is water. Therefore, ozone is used because it does not create water molecules like H.sub.2 O.sub.2.
In such a wet chemistry station which uses ozone, an uneven distribution of the gas through the bath will produce uneven results. That is, parts in various locations of the tank will be treated in differing manners, yielding uncertain results.
Attempts have been made to inject ozone in various locations into the tank. What is needed is a diffusion scheme to evenly disburse the gas so that all locations of the bath are evenly oxygenated.
The present invention provides for even distribution of ozone through a sparger plate in a sulfuric bath.